One week ago, at Upstate New York, Paul Vincent was killed from an unnamed assailant. Vincent was the new identity of former A.I.M. agent Paul Winston, who entered Witness Protection. The next day, the police goes to investigate his apartment. As the police finds an A.I.M. uniform in Vincent's apartment, agents Diamondback and Dum Dum Dugan appear, announcing that they will take over the case.

Later, at the Helicarrier, Diamondback and Dugan talk with Captain America about the murder. Winston is the second protected witness to be killed in less than a week. Diamondback shows Cap a picture they got from a security camera and reveals the killer: a new Scourge.

Wondering how did Scourge find about the protected witnesses, Dugan believes someone is feeding him information from Witness Protection files. Winston was ex-A.I.M., and the first victim was an A.I.M. defector, and they both entered the system in the last six months. Cap deduces that the new Scourge is attacking recent additions, so he orders Diamondback and Dugan to investigate every detail on the witnesses they have placed in the last year, while Sharon starts digging intel on the new Scourge. Cap goes to find the traitor.

As Diamondback and Dugan prepare to leave, Dugan remarks that Diamondback wants to impress Rogers, showing surprise that she and Cap used to be together. Diamondback replies that she and Rogers were together when she used to work for the bad guys, amusing Dugan.

On a government building, Cap meets up with three agents who have access to the compromised files, believing one of them to be the traitor. Suddenly, one of the agents pulls out a gun and proclaims loyalty to Hydra. Attacking Cap, he jumps out of the window and tries to escape using a jetpack. However, Cap takes him down by hitting his jetpack with his shield. Although Cap tries to make the Hydra agent confess who is he working for, the agent commits suicide with a cyanide pill. Sharon contacts Cap and asks him about what happened. Cap replies that they just don't have a traitor, they have infiltrators.

Diamondback goes to the new home of Leon Murtaugh, aka Viper. Although Diamondback asks him about Scourge, he claims not to know anything. Suddenly, Scourge blasts through the house and kills Leon. Diamondback tries to apprehend him, but Scourge brutally beats her down. As Scourge leaves, Diamondback realizes she knows him before falling unconscious.